Numerous systems are known for securing a structural member to a substrate. For example, U.S. Pat. No. 4,946,325, incorporated by reference herein, describes a "mechanical" anchor stud having an expansion anchor element for gripping the sidewalls (bore) of a hole in a surface (substrate). As is typical of mechanical anchors, the anchor element exerts a sizeable outward radial force on the sidewalls of the hole.
In certain instances, mechanical-type anchors are disadvantageous. For example, in securing a balustrade (structural member) to a narrow strip of concrete (substrate), the outward radial force exerted by the anchor element may cause fracturing of the concrete.
"Chemical" anchoring systems are also known. A typical chemical anchoring system requires that a hole be drilled in a substrate, a quantity of adhesive (such as epoxy) be disposed in the hole, and an externally-threaded stud be inserted into the hole. The adhesive is typically contained in a capsule, which is shattered by insertion of the stud. The stud may also have a chisel point for aiding in mixing a two-part adhesive. The adhesive, upon curing, firmly retains the externally-threaded stud in the hole, and a structural member can be secured (e.g., with a nut) to a portion of the stud that extends (protrudes) beyond the surface of the substrate.
In certain instances, it may not be desirable to use an anchor stud at all, whether it be of the mechanical or chemical type, simply because it is non-aesthetic to have a stud projecting out of a surface. For example, it may be desirable to employ a decorative bolt (i.e., rather than a nut on a stud) to mount the structural member to the substrate. Additionally, it may not be desirable to secure a structural member to a substrate with an anchor stud because, upon removal of the structural member, the stud would remain protruding from the surface. If a flat surface is desired, the protruding portion of the stud, to which a nut would thread onto, must be cut off. Later, if it is desired to remount the structural member, the embedded portion of the stud must be completely drilled out, and a new anchor stud installed in the substrate.